Capillary Carbon black

Figure 1.17 Separation of large ring polycyclic aroaatic hydrocarbons extracted from carbon black on a 1.8 x 0.2 n I.D. fused silica capillary column packed with 3 micrometer spherical octadecylsllanized silica gel eluted with a stepwise solvent gradient at a flow rate of 1.1 mlcroliters/min with an inlet pressure of about 360 atmospheres. Under isocratic conditions this column yielded ca. 225,000 theoretical plates. (Reproduced with permission from ref. 238. Copyright Friedr. Vieweg t Sohn).

These phases are composed of adsorbing materials molecular sieves, alumina, porous glass and gels (such as Chromosorb 100, Porapak and PoraPLOT1 ), and graphitised carbon black. They are mainly used to separate gases or volatile compounds. Capillary columns made by deposition of these materials in the form of very fine particulates are called PLOT (porous layer open tubular) columns. 

Type IV isotherms are characterized by the presence of a hysteresis loop (i.e., adsorption and desorption branches are not coincident) due to the capillary condensation on the mesopores. They are characteristic of adsorbents that have a wide proportion of mesopores (i.e., compacted carbon blacks under pressure, nanostructured carbons prepared using mesoporous silica as templates, etc.). 

In all experiments, gases, liquids, water fraction as well as solid residue were obtained as products and analyzed on different capillary GC columns and registered with TCD-and FID-detectors. The reactor sand used and the fillers in the overflow and cyclone were combusted in a furnace at 810°C to constant weight. The loss in weight was balanced as carbon black. 

Figure 3. SFC chromatogram of a carbon black extract. Conditions n-pentane mobile phase at 210°C 32 m x 75 pm i.d. fused silica capillary column coated with a 0.25- Jm film of crosslinked 50% phenyl methylphenylpolysiloxane, UV-absorption at 214 nm, asymptotic density program from 0.07 g/mL (26.7 atm) to 0.24 g/mL according to the equation 13 8...

Carbon black has also been supported on polythene moulding powder by heating a mixture of the black with polythene in air to 160-170°C so that the polythene softened sufficiently for the black to adhere to it, and on the walls of glass capillary columns and on glass beads, Carbon black may with advantage be modified by addition of a liquid such as squalane. 

Figure 29 8 illustrates the separation of polycyclic aromatic hydrocarbons extracted from a carbon black, Detection was by fluorescence excited at two differeni wavelengths. Note the selectivity provided by this technique, The chromatogram was obtained b> using a 40 m X. SO pm inside-diameter capillary coated with a 0,25-pm film of S0% phenylpolysiloxane. The mobile phase was pentane at 2l(rc. and the following pro-gram was used initial mobile-phase density held at... 

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